The reason that I asked about bash, was that your PS looks like the tcsh PS provided by apple. That command should work perfectly in bash. If you already have not done so, can you attempt to enter a bash shell using /bin/bash and then execute the command; I have had problems with Terminal.app where I chsh to bash, but it still used tcsh.

Something I did not notice last night was that for some reason your terminal appears to want to su all of your commands. If you look at the error line, you will see that su is what is having problems.
su: FEATURES=-collision-protect: Command not found.

Perhaps the shell in your Terminal->Preferences is set to /bin/su, one of your users shells is set to /bin/su, there is some sort of sudo shell (if it exists) on your computer, or the command that you issued to change to root caused this to happen.

If you get additional errors preceded by su: then you should check your Terminal->Preferences and chsh for your intial login user and for root. If you just 'echo $SHELL` it will ONLY report the initial login shell of your initial user, unless you update your current users environment profiles, and can lead you to believe that your shell is different than the current setting.